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Abstract: A polymeric-inorganic composite cation-exchanger, i.e. Nylon-6,6 Sn(IV) phosphate was synthesized via mixing of polymer Nylon-6,6 into the matrices of inorganic precipitate of Sn(IV) phosphate to form composite cation-exchanger. Ion-exchange capacity (IEC), ion-exchange properties, thermal stability and distribution behavior, etc. were also carried out to understand the cation-exchange behavior of the material. The physico-chemical properties of the material were determined using AAS, CHN elemental analysis, FTIR, TGA-DTA, XRD, and SEM studies. On the basis of distribution studies, the material was found to be highly selective for Hg(II), a highly toxic environmental pollutant. Using this electroactive composite material, a new heterogeneous precipitate based selective membrane electrode was fabricated for the determination of Hg(II) ions in solutions. The membrane electrode is mechanically stable, with a quick response time, and can be operated within a wide pH range. The selectivity coefficients for different cations determined by mixed solution method were found to be less than unity. The electrode was also found to be satisfactory in potentiometric titrations. [Copyright &y& Elsevier]

Abstract: An organic–inorganic nanocomposite cation-exchanger, i.e. poly-o-toluidine Zr(IV) phosphate was synthesized via sol–gel mixing of an electrical conducting polymer poly-o-toluidine into the matrices of inorganic precipitate of Zr(IV) phosphate. The ion-exchange capacity, chemical stability, effect of eluant concentration, elution behavior, pH titration and thermal studies were also carried out to understand the ion-exchange capabilities. The physico-chemical properties of the material were determined using AAS, CHN elemental analysis, FTIR, TGA–DTA, XRD, TEM and SEM studies. On the basis of distribution studies, the material was found to be highly selective for Hg(II). Its selectivity was examined by achieving some important binary separations like Hg(II)–Pb(II), Hg(II)–Cu(II), Hg(II)–Co(II), Hg(II)–Fe(III), Hg(II)–Sr(II), etc. on its column. This material possessed d.c. electrical conductivity in the semi-conducting range, i.e. 10−3 to 10−2 Scm−1; measured by four-in-line probe d.c. electrical conductivity-measuring technique. The d.c. electrical conductivity of the composite material was found stable upto 110°C for the composites under ambient conditions. [Copyright &y& Elsevier]

A new and novel electrically conducting ‘polymeric–inorganic’ composite cation-exchange material; polyaniline Sn(IV) tungstoarsenate was prepared by incorporating polyaniline into inorganic ion-exchanger material. It possessed improved ion-exchange capacity, high chemical and thermal stabilities, reproducibility and selectivity for some specific metal ions. Kinetic study of exchange for some divalent metal ions of alkaline earths and transition metals was carried out under the conditions favoring a particle diffusion-controlled ion-exchange phenomenon and some physical parameters such as self diffusion coefficient D0, energy of activation Ea and entropy of activation ΔS* were determined. The temperature dependence of electrical conductivity of this composite material with increasing temperatures was measured by using 4-in-line-probe DC electrical conductivity measuring-technique. The conductivity values lie in the semiconductor region, i.e. in the range of 10−3 S cm−1 that follow the Arrhenius equation. The energy of activation of electrical conduction for the composite was also calculated. [Copyright &y& Elsevier]